1. Field of the Invention
This invention relates to the production of polyalkylene polyamines, and more particularly to the production of predominantly linearly extended polyalkylene polyamines by reacting alkylenediamines with alkylene glycols or alkanolamines using a phosphorus amide catalyst.
2. Description of the Prior Art
The preparation of predominantly non-cyclic, i.e., linear, polyalkylene polyamines is described in U.S. Pat. No. 4,036,881 (Brennan I). The Brennan I patent is one of several patents, including for example U.S. Pat. No. 4,044,053 (Brennan II), involving the production of predominantly noncyclic polyalkylene polyamines using a phosphorus-containing catalyst. The Brennan I patent describes an improved process for reacting alkanolamines with alkylenediamines to selectively produce predominantly noncyclic products. These patents disclose phosphorus-containing catalysts encompassing a wide variety of phosphorus acid or acid derivative compounds. There is no disclosure or indication that phosphorus amide compounds would provide effective alternative catalysts. Instead, the present invention is based on the unexpected discovery that increased conversion rates for polyalkylene polyamine preparation can be achieved through the use of phosphorus amide catalysts in place of the phosphorus-containing substances previously disclosed.